CN101636011B - Hollow heat source - Google Patents

Abstract

A hollow heat source comprises a hollow substrate, a heating layer and at least two electrodes, wherein, the heating layer is arranged on the surface of the hollow substrate; the two electrodes are arranged at intervals and are electrically connected with the heating layer respectively; the heating layer comprises a carbon nano tube layer which comprises a plurality of mutually wound carbon nano tubes.

Description

hollow heat source

technical field

The invention relates to a hollow heat source, in particular to a hollow heat source based on carbon nanotubes.

Background technique

Heat sources play an important role in people's production, life and scientific research. The hollow heat source is a kind of heat source, and its characteristic is that the hollow heat source has a hollow structure, and the object to be heated is arranged in the hollow of the hollow structure to heat the object. Therefore, the hollow heat source can heat all parts of the object to be heated at the same time. Wide area, uniform heating and high efficiency. Hollow heat sources have been successfully used in industrial fields, scientific research fields, or living fields, such as factory pipes, laboratory heating furnaces, or electric ovens for kitchen utensils, etc.

The basic structure of a hollow heat source usually includes a base and an electric heating layer arranged on the base. By passing an electric current through the electric heating layer to generate Joule heat, the temperature of the electric heating layer is raised to heat the object. The electric heating layer of the existing hollow heat sources is usually formed by laying or winding metal wires, such as chromium-nickel alloy wires, copper wires, molybdenum wires or tungsten wires. However, the use of metal wire as the electric heating layer has the following disadvantages: first, the surface of the metal wire is easily oxidized, resulting in an increase in local resistance and thus being blown, so the service life is short; second, the metal wire is gray body radiation, so the heat The radiation efficiency is low, the radiation distance is short, and the radiation is uneven; third, the metal wire has a high density, a large weight, and is inconvenient to use.

In order to solve the problem of metal wire as an electric heating layer, carbon fiber has become a hot spot in the research of electric heating layer materials because of its good black body radiation performance and low density (see "Development Foreground and Market Analyze of Carbon Fiber", Wang Hai-ying, Hi-Tech Fiber & Application, Vol8, P765 (2007)). When carbon fiber is used as an electric heating layer, it usually exists in the form of carbon fiber paper. The carbon fiber paper includes a paper substrate and pitch-based carbon fibers randomly distributed in the paper substrate. Wherein, the paper substrate includes a mixture of cellulose fiber and resin, etc., and the pitch-based carbon fiber has a diameter of 3-6 mm and a length of 5-20 microns.

However, the use of carbon fiber paper as the heating layer has the following disadvantages: First, the thickness of carbon fiber paper is relatively large, generally tens of microns, which makes it difficult for the hollow heat source to be made into a microstructure, and cannot be applied to the heating of micro devices. Second, because the carbon fiber paper contains the paper base material, the carbon fiber paper has a high density and a large weight, which makes it inconvenient to use the hollow heat source using the carbon fiber paper. Third, due to the random distribution of pitch-based carbon fibers in the carbon fiber paper, the carbon fiber paper has low strength, poor flexibility, and is easy to break, which limits its scope. Fourth, the electrothermal conversion efficiency of carbon fiber paper is low, which is not conducive to energy saving and environmental protection.

In view of this, it is indeed necessary to provide a hollow heat source, which has high heating efficiency, high strength and toughness, long life, low cost, can be applied to macroscopic and microscopic devices, and has good practical application performance.

Contents of the invention

A hollow heat source, which includes: a hollow base; a heating layer, the heating layer is arranged on the surface of the hollow base; and at least two electrodes, and the at least two electrodes are arranged on the surface of the heating layer at intervals, and respectively The heating layer is electrically connected, wherein the heating layer includes a carbon nanotube layer, and the carbon nanotube layer includes a plurality of intertwined carbon nanotubes.

Compared with the prior art, the hollow heat source has the following advantages: First, carbon nanotubes can be conveniently made into carbon nanotube layers of any size, which can be applied to both macroscopic and microscopic fields. Second, carbon nanotubes have a lower density than carbon fibers, so the hollow heat source using carbon nanotube layers has lighter weight and is easier to use. Third, the carbon nanotube layer has high electrothermal conversion efficiency and low thermal resistivity, so the hollow heat source has the characteristics of rapid temperature rise, small thermal hysteresis, and fast heat exchange speed. Fourth, the carbon nanotubes in the carbon nanotube layer are arranged in disorder, have good toughness, and can be bent and folded into any shape without breaking, so they have a long service life.

Description of drawings

Fig. 1 is a schematic structural view of the hollow heat source provided by the first embodiment of the technical solution.

FIG. 2 is a schematic cross-sectional view along line II-II of FIG. 1 .

Fig. 3 is a scanning electron micrograph of the carbon nanotube layer of the embodiment of the technical solution.

Fig. 4 is a photo of the carbon nanotube layer of the embodiment of the technical solution.

Fig. 5 is a schematic structural view of the hollow heat source provided by the second embodiment of the technical solution.

FIG. 6 is a schematic cross-sectional view of line VI-VI in FIG. 5 .

Fig. 7 is a schematic structural diagram of the hollow heat source provided by the third embodiment of the technical solution.

FIG. 8 is a schematic cross-sectional view along line VIII-VIII of FIG. 7 .

Detailed ways

The hollow heat source of the technical solution will be described in detail below in conjunction with the accompanying drawings.

Please refer to Fig. 1 and Fig. 2, the first embodiment of the technical solution provides a hollow heat source 100, the hollow heat source 100 includes a hollow base 102; a heating layer 104, the heating layer 104 is arranged on the inner surface of the hollow base 102 a reflective layer 108, the reflective layer 108 is located at the periphery of the heating layer 104, and is arranged on the outer surface of the hollow substrate 102; a first electrode 110 and a second electrode 112, the first electrode 110 and the second electrode 112 are arranged at intervals on the surface of the heating layer 104 and electrically connected to the heating layer 104 respectively; an insulating protection layer 106 is disposed on the inner surface of the heating layer 104 .

The material of the hollow base 102 is not limited, and it is used to support the heating layer 104, and it can be a hard material, such as: ceramics, glass, resin, quartz, plastic, and the like. The hollow base 102 can also be made of flexible materials, such as resin, rubber, plastic or flexible fibers. When the hollow base 102 is made of flexible material, the hollow heat source 100 can be bent into any shape as required during use. The shape and size of the hollow base 102 are not limited, as long as it has a hollow structure, it can be tubular, spherical, cuboid, etc., it can be a fully closed structure, or a semi-closed structure, which can be changed according to actual needs . The shape of the cross-section of the hollow base 102 is not limited, and may be circular, arc-shaped, rectangular and so on. In this embodiment, the hollow base 102 is a hollow ceramic tube with a circular cross section.

The heating layer 104 is disposed on the inner surface of the hollow base 102 for heating the inner space of the hollow base 102 . The heating layer 104 includes a carbon nanotube layer. The carbon nanotube layer itself has a certain viscosity, and can be placed on the surface of the hollow substrate 102 by utilizing its own viscosity, or can be arranged on the surface of the hollow substrate 102 through an adhesive. The adhesive is silica gel. The length, width and thickness of the carbon nanotube layer are not limited and can be selected according to actual needs. The carbon nanotube layer provided by the technical solution has a length of 1-10 cm, a width of 1-10 cm, and a thickness of 1 micron-2 mm. It can be understood that the thermal response speed of the carbon nanotube layer is related to its thickness. In the case of the same area, the thicker the carbon nanotube layer, the slower the thermal response speed; conversely, the smaller the carbon nanotube layer thickness, the faster the thermal response speed.

The carbon nanotube layer includes intertwined carbon nanotubes, please refer to FIG. 3 . The carbon nanotubes attract and intertwine with each other through van der Waals force to form a network structure. In the carbon nanotube layer, the carbon nanotubes are uniformly distributed and arranged randomly, so that the carbon nanotube layer is isotropic; the carbon nanotubes are intertwined, so the carbon nanotube layer has good flexibility and can be bent Fold into any shape without breaking, see picture 4. The carbon nanotubes in the carbon nanotube layer include one or more of single-wall carbon nanotubes, double-wall carbon nanotubes and multi-wall carbon nanotubes. The single-walled carbon nanotubes have a diameter of 0.5 nm to 10 nm, the double-walled carbon nanotubes have a diameter of 1.0 nm to 15 nm, and the multi-walled carbon nanotubes have a diameter of 1.5 nm to 50 nm. The length of the carbon nanotube is greater than 50 microns. In this embodiment, the length of the carbon nanotubes is preferably 200-900 microns.

In this embodiment, the heating layer 104 is a carbon nanotube layer with a thickness of 100 microns. The length of the carbon nanotube layer is 5 cm, and the width of the carbon nanotube layer is 3 cm. The carbon nanotube layer is disposed on the inner surface of the hollow substrate 102 by utilizing the viscosity of the carbon nanotube layer itself.

The first electrode 110 and the second electrode 112 are arranged at intervals and are respectively electrically connected to the heating layer. The first electrode 110 and the second electrode 112 can be arranged on the same surface of the heating layer 104 or on different surfaces of the heating layer 104 superior. The first electrode 110 and the second electrode 112 can be disposed on the surface of the heating layer 104 through an adhesive or conductive adhesive (not shown) of the carbon nanotube layer. The conductive adhesive can better fix the first electrode 110 and the second electrode 112 on the surface of the carbon nanotube layer while realizing the electrical contact between the first electrode 110 and the second electrode 112 and the carbon nanotube layer. A voltage can be applied to the heating layer 104 via the first electrode 110 and the second electrode 112 . Wherein, the first electrode 110 and the second electrode 112 are spaced apart, so that the heating layer 104 using the carbon nanotube layer is connected with a certain resistance value to avoid short circuit when energized and heated. Preferably, the first electrode 110 and the second electrode 112 are arranged at two ends of the hollow substrate 102 at intervals, and are arranged around the surface of the heating layer 104 .

The first electrode 110 and the second electrode 112 are conductive films, metal sheets or metal leads. The material of the conductive thin film can be metal, alloy, indium tin oxide (ITO), antimony tin oxide (ATO), conductive silver paste, conductive polymer and the like. The conductive film can be formed on the surface of the heating layer 104 by physical vapor deposition, chemical vapor deposition or other methods. The material of the metal sheet or the metal lead may be copper sheet or aluminum sheet or the like. The metal sheet can be fixed on the surface of the heating layer 104 by a conductive adhesive.

The first electrode 110 and the second electrode 112 can also be a carbon nanotube structure. The carbon nanotube structure is disposed on the outer surface of the heating layer 104 . The carbon nanotube structure can be fixed on the outer surface of the heating layer 104 by its own adhesive or conductive adhesive. The carbon nanotube structure includes aligned and uniformly distributed metallic carbon nanotubes. Specifically, the carbon nanotube structure includes at least one ordered carbon nanotube film or at least one carbon nanotube long line.

In this embodiment, preferably, two ordered carbon nanotube films are respectively arranged at both ends along the length direction of the hollow substrate 102 as the first electrode 110 and the second electrode 112 . The two ordered carbon nanotube films surround the outer surface of the heating layer 104 and form an electrical contact with the heating layer 104 through a conductive adhesive. The conductive adhesive is preferably silver glue. Since the heating layer 104 in this embodiment also adopts a carbon nanotube layer, there is a small ohmic contact resistance between the first electrode 110 and the second electrode 112 and the heating layer 104, which can improve the utilization rate of the hollow heat source 100 for electric energy .

The reflective layer 108 is used to reflect the heat emitted by the heating layer 104 so as to effectively heat the inner space of the hollow substrate 102 . The reflective layer 108 is located on the periphery of the heating layer 104 , and in this embodiment, the reflective layer 108 is disposed on the outer surface of the hollow substrate 102 . The reflective layer 108 is made of a white insulating material, such as metal oxide, metal salt or ceramic. The reflective layer 108 is disposed on the outer surface of the hollow substrate 102 by sputtering or coating. In this embodiment, the reflective layer 108 is preferably made of Al2O3, with a thickness of 100 microns-0.5 mm. The reflective layer 108 is deposited on the outer surface of the hollow substrate 102 by sputtering. It can be understood that the reflective layer 108 is an optional structure, and when the hollow heat source 100 does not include a reflective layer, the hollow heat source 100 can also be used for external heating.

The insulating protection layer 106 is used to prevent the hollow heat source 100 from forming electrical contact with the outside world during use, and at the same time prevent the carbon nanotube layer in the heating layer 104 from absorbing foreign impurities. In this embodiment, the insulating protection layer 106 is disposed on the inner surface of the heating layer 104 . The material of the insulating protection layer 106 is an insulating material, such as rubber, resin and the like. The thickness of the insulating protection layer 106 is not limited, and can be selected according to actual conditions. Preferably, the insulating protection layer 106 has a thickness of 0.5-2 millimeters. The insulating protection layer 106 can be formed on the surface of the heating layer 104 by coating or sputtering. It can be understood that the insulating protection layer 106 is an optional structure.

The hollow heat source 100 provided by this embodiment specifically includes the following steps during application: providing an object to be heated; placing the object to be heated at the center of the hollow heat source 100; passing the hollow heat source 100 through the first electrode 110 and the second After the connecting wire of the electrode 112 is connected to a power supply voltage of 1V-20V, the heating power is 1W-40Wh, and the hollow heat source can radiate electromagnetic waves with longer wavelengths. The temperature of the surface of the heating layer 104 of the hollow heat source 100 is found to be 50° C. to 500° C. by measuring the infrared thermometer AZ8859, which is used to heat the object to be heated. It can be seen that the carbon nanotube layer has high electrothermal conversion efficiency. Since the heat on the surface of the heating layer 104 is transferred to the object to be heated in the form of thermal radiation, the heating effect will not be greatly different due to the distance from the hollow heat source 100 to each part of the object to be heated, and the uniformity of the object to be heated can be achieved. heating. For an object with a black body structure, when the corresponding temperature is 200°C to 450°C, it can emit thermal radiation (infrared rays) invisible to the human eye. At this time, the thermal radiation is the most stable and efficient, and the generated thermal radiation Heat max.

When the hollow heat source 100 is in use, it can be directly contacted with the surface of the object to be heated or placed at a distance from the object to be heated, and the heat radiation can be used for heating. The hollow heat source 100 can be widely used in factory pipelines, laboratory heating furnaces or electric ovens for kitchen utensils and the like.

The hollow heat source 100 provided in this embodiment has the following advantages: one, the heating layer 104 is a carbon nanotube layer, and the carbon nanotube has strong corrosion resistance, so that it can work in an acidic environment; Nanotubes are 100 times stronger than steel with the same volume, but their weight is only 1/6. Therefore, the hollow heat source 20 using carbon nanotubes has higher strength and lighter weight; thirdly, the carbon nanotubes The carbon nanotubes in the layer are arranged in disorder, have good toughness, and can be bent and folded into any shape without breaking, so it has a long service life.

Please refer to Fig. 5 and Fig. 6, the second embodiment of the technical solution provides a hollow heat source 200, the hollow heat source 200 includes a hollow base 202; a heating layer 204, the heating layer 204 is arranged on the inner surface of the hollow base 202 a reflective layer 208, the reflective layer 208 is located at the periphery of the heating layer 204; a first electrode 210 and a second electrode 212, the first electrode 210 and the second electrode 212 are arranged at intervals on the surface of the heating layer 204, and are respectively connected with The heating layer 204 is electrically connected; an insulating protection layer 206 is disposed on the inner surface of the heating layer 204 . The structure of the hollow heat source 200 provided in the second embodiment is basically the same as that of the hollow heat source 100 provided in the first embodiment. The outer surface. The structures and materials of the hollow substrate 202 , the heating layer 204 , the reflective layer 208 , the first electrode 210 and the second electrode 212 are the same as those of the first embodiment.

7 and 8, the third embodiment of the present technical solution provides a hollow heat source 300, the hollow heat source 300 includes a hollow base 302; a heating layer 304; a reflective layer 208; a first electrode 310 and a first The two electrodes 312 , the first electrode 310 and the second electrode 312 are arranged at intervals on the surface of the heating layer 204 and are electrically connected to the heating layer 304 respectively. The structure of the hollow heat source 300 in the third embodiment is basically the same as that of the hollow heat source 100 in the first embodiment, the difference is that the heating layer 304 is arranged on the outer surface of the hollow substrate 302, and the reflective layer 308 is arranged on the heating layer. On the outer surface of 304, since the heating layer 304 is disposed between the hollow base 302 and the reflective layer 308, there is no need for an insulating protective layer, and the positions of the heating layer 304 and the reflective layer 308 are different. The structures and materials of the hollow base 302, the heating layer 304, and the reflective layer 308 in the third embodiment are the same as those in the first embodiment.

In addition, those skilled in the art can also make other changes within the spirit of the present invention. Of course, these changes made according to the spirit of the present invention should be included within the scope of protection claimed by the present invention.

Claims (15)

1. hollow heat source, it comprises:

One hollow base;

One zone of heating, this zone of heating is arranged at the surface of hollow base; And

At least two electrode gap settings also are electrically connected with zone of heating respectively;

It is characterized in that described zone of heating comprises a carbon nanotube layer, and this carbon nanotube layer comprises a plurality of CNTs that twine each other through Van der Waals force.

2. hollow heat source as claimed in claim 1 is characterized in that described hollow heat source further comprises a reflector, and said reflector is arranged at the periphery of zone of heating.

3. hollow heat source as claimed in claim 2 is characterized in that described hollow heat source further comprises an insulating protective layer, and this insulating protective layer is arranged at the surface of zone of heating.

4. hollow heat source as claimed in claim 3 is characterized in that described zone of heating is arranged at the outer surface of hollow base, and described reflector is arranged at the outer surface of zone of heating, and zone of heating is between hollow base and reflector.

5. hollow heat source as claimed in claim 3 is characterized in that described zone of heating is arranged at the inner surface of hollow base, and described reflector is arranged at the outer surface of hollow base, and described insulating protective layer is arranged at the inner surface of zone of heating.

6. hollow heat source as claimed in claim 3 is characterized in that described zone of heating is arranged at the inner surface of hollow base, and described reflector is arranged between zone of heating and the hollow base, and described insulating protective layer is arranged at the inner surface of zone of heating.

7. hollow heat source as claimed in claim 2 is characterized in that, the material in described reflector is metal oxide, slaine or pottery, and its thickness is 100 microns-0.5 millimeter.

8. hollow heat source as claimed in claim 1 is characterized in that, attracts each other through Van der Waals force between the CNT in the described carbon nanotube layer, forms network-like structure.

9. hollow heat source as claimed in claim 1 is characterized in that, said even carbon nanotube distributes, random arrangement, and carbon nanotube layer is isotropism.

10. hollow heat source as claimed in claim 1 is characterized in that, the thickness of described carbon nanotube layer is 1 micron to 2 millimeters.

11. hollow heat source as claimed in claim 1 is characterized in that, the length of described CNT is greater than 50 microns, and diameter is less than 50 nanometers.

12. hollow heat source as claimed in claim 1 is characterized in that, said at least two electrodes are arranged at the same surface or the different surfaces of zone of heating.

13. hollow heat source as claimed in claim 1 is characterized in that, the material of said at least two electrodes is metal, alloy, indium tin oxide, conductive silver glue, conducting polymer or conductive carbon nanotube.

14. hollow heat source as claimed in claim 1 is characterized in that, the material of said hollow base is flexible material or hard material, and said flexible material is plastics or flexible fiber, and said hard material is pottery, glass, resin, quartz.

15. hollow heat source as claimed in claim 1 is characterized in that, at least one electrode is a carbon nano tube structure in said at least two electrodes, and this carbon nano tube structure comprises at least one ordered carbon nanotube film or at least one carbon nanotube long line.

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